I think this is overly simplified. The other reason people fight is that they feel they have no chance otherwise or they feel like their values are attacked. Small group that fight dont think they are stronger, they think they are right and willing to sacrifice (or feel like they have nothing to loose, or just feel hate so much).

Also, more confident about own power go to war because they want to. See WWII - it does not matter how many concessions would be done to nazi, the ideology itself demanded the war. That is why it happened.

Or look at Iran war. Iran was making concessions, USA attacked anyway because it wanted to. American leadership valued war and lethality and wanted to demonstrate it. Irans strategic appeasement was seen as sign of weakness.

Or look at Canada trade war. Canada does not think it is stronger, it thinks concessions will lead to further bullying from stronger neighborhood.

The parent point still stands. Poland and England and everybody could have just not resisted, and accepted occupation, then there would be no war. (Most probably slavery or something, but not war).

Iran didn’t agree to all US/Israel points. Iran felt that they have leverage and can resist. (On the other side, Iran’s leverage/power was not obvious enough to US administration, so US started the war hoping to win quickly).

Guerrilla groups fight because they believe they can win / make s difference, not necessarily in military sense. e.g. Vietnam didn’t win the war on the battle field, US got politically exhausted/tired and retreated (non-military victory is still a victory)

In all cases groups that fight believe they can win somehow eventually. Brainwashed suicide bombers, also believe (less due to ambiguity, more due to brainwashing part)